Computing devices such as mobile telephones, tablets, laptops and desktops have become widely available in recent years. These devices can be equipped with processors, memory and the capability to communicate through local and wide area networks, including the Internet. These devices can also be equipped with output devices such as displays, image-sensing devices and sound-sensing devices that allow the device user to record, display and communicate content to other computing devices and other device users.
Some computing devices, including mobile phones and tablets, are equipped with location sensing devices. Location sending devices can include global positioning system (GPS) sensors, inertial sensors, flux-gate compasses and triangulation systems based on cellular telephone signals. These devices permit a computing device to determine its absolute or relative position or orientation to varying degrees of resolution.